Dental flasks



July 28, 1959 5L HARRIS 2,896,259

DENTAL FLASKS 2 Sheets-Sheet 1 Filed Nov. 25, 1957 a; R Q

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DENTAL FLASKS 2 Sheets-Sheet 2 I! I I Filed Nov; 25, 1957 INVENTOR. SAMUE L HARRIS BYf W United States Patent 2,896,259 DENTAL FLASKS Samuel Harris, Forest Hills, NY. Application November 25, 1957, Serial No. 698,654 3 Claims. (Cl. 18-33) This invention relates to dental flasks wherein artificial dentures are formed and more particularly to a three member hinged molding flask that is especially adapted for processing acrylic teeth to extensive metal bridgework or for processing acrylic teeth to a plate member.

The present invention is an improvement to the dental flask disclosed in my earlier patent, No. 2,539,740. In that flask, there is provided a shell-like base member that accommodates a convex platform piece over which investment material is molded. A metal bridge having wax teeth formed thereon in the places where acrylic teeth are ultimately to be provided is arched over, and embedded, in the convex surface of the investment material. An upper flask member hinged to one end of the base member is filled with investment material whereupon it is pivoted into engagement with one half of the bridgework embedded in the investment material formed on the platform. A second upper flask member hinged to the other end of the base member is similarly filled with investment material and pivoted into engagement with the other half of the embedded bridgework. After the investment material has hardened and the flask opened, an impression of the wax teeth is found in the investment material of the upper flask members. The wax can then be melted from the bridgework and a mold is thus provided into which acrylic material is placed. By reclosing and tightening the flask, the acrylic material in the form of teeth conforming to the pattern of the mold, is adhered to the metal bridgework.

While the flask of the earlier patent has many advantages, one of which is that the acrylic material is readily viewable by the dental technician and hence the coloring and shading of the dentures can be altered and adjusted during the process of forming the teeth, it has been found that the improvement made by the present invention is of great value.

In the above outline of how the earlier'flask is utilized, it will be noted that an impression of wax teeth is formed in the investment material. Of course, it will be appreciated that a great deal of care is given in shaping these teeth to compliment the facial characteristics of the person for whom'the denture is to be prepared. Similarly the final denture must be produced with great fidelity to the wax teeth. However, even the slightest lateral shifting of the upper flask members when they are being brought into engagement with the remainder of the flask will result in the acrylic teeth being less than a faithful reproduction of the original wax teeth.

Since the various components of the dental flask are formed by casting and a minimum amount of machine finishing is performed thereon, the flask is a relatively loose fitting assembly and some lateral shifting of the parts was encountered when using the flask with the dire consequences noted above.

It is the object of the present invention to provide a dental flask which, when in use, will be snug fitting so that there is no relative shifting of the component parts of the flask.

In carrying out the invention there is provided in addition to the parts or components heretofore disclosed, a

locking member which is fitted over the platform piece "."ice

placed in the base member. When the investment material is molded over the platform piece, ridges of the locking member project therefrom. The ridges project into the investment material of the upper flask members when they are brought into operative position. Therefore when the investment material hardens to form the mold, an absolutely tight assembly is provided.

Features and advantages of this invention will be gained from the foregoing and the description of a preferred embodiment thereof which follows.

In the drawings:

Figure 1 is a front elevational view, in section, of the dental flask showing the upper flask members in open position;

Figure 2 is a plan view of the apparatus of Figure 1',

Figure 3 is a front elevational view partly in section, showing the flask in assembled or molding position; and

Figure 4 is a view taken along line 4-4 of Figure 3.

Referring to the drawings, a base flask member 10 is shown having a central cavity 11 of generally rectangular form and a size to accommodate a removable platform piece 12. The platform piece comprises a base portion 13 that fits substantially into cavity 11, and an upper convex portion 14. The upper convex portion is shown as two spaced apart upright members, as it would be in the event that a full dental plate was being molded. However, if a bridge was being made the convex portion 14 would extend across the full width of cavity 11 as shown in my earlier patent. A tapered plug 18 fits into an aperture 19 formed in the bottom of base member 10. This is provided so that platform piece 12 containing hardened investment material and the finished denture may be readily removed from member 10 after the denture making operation is completed.

A pair of side wall. members 15 are removably fastened to base member 10 as by interlocking pins 16 provided on the side walls and projecting into appropriately placed holes in the base member. With the platform piece in place, the spaced apart upper convex members 14 abut the sidewalls 15. A locking member 17 is also provided for superposing above platform 12 and it too is formed with a base portion 20 that fits in the central cavity of base member 10 atop base 13 of platform 12. The upper spaced apart portions 21 of member 17 are formed on their underside to conform to the outline of platform 12 upon which member 17 rests. The outer surface of portions 21 may best be described by reference to Figure 4 wherein it is seen that the edge of the member abutting the side walls 15, is, aligned with the top of the side wall, while the inner edge or prong 22 reaches substantially above the side wall. Of course the upper portion 21 of member 17 may consist of prong-like ridges that are spaced from the side walls 15 and extend above the height of the side walls. However, by forming member 17 as shown in drawings with the entire space between the inner edges 22 and the side walls 15 occupied by member 17 a substantial amount of investment material will be saved when using the flask.

One end of base member 10 is for-med with a pair of projecting arms 23 which serve to support a pin 24. A hook-like appurtenance 25 formed on upper flask member 26 engages the pin in the fashion of a hinge so that the flask member 26 can be pivoted thereabout. Member 26 is also formed with walls 27 which when the member is in closed position (Figure 3) conform to the contour of side walls 15. A U-shaped lug 30 formed atop member 26 is utilized to lock the flask as will hereinafter be described. An aperture 29 is provided in the upper flask member to facilitate the removal of hardened investment material therefrom after the flask has been used.

The other end of base member 10 is similarly pro- 7 3 vided with a pair of projecting arms 31 which serve to support pin 32. A hook-like appurtenance 33 formed on the second upper flask member 34 engages pin 32 so that flask member 34 can be-pivoted thereabout to a closed position. When in such position, the walls 35 of member 34 conform to the contour of side walls 15. e As in the case of member 26, member 34 also is formed with a U-shaped lug 36. member 34 to facilitate the removal of hardened investment material therefrom after the rflask has been used.

A clamping device is provided for locking the three flask members into a rigid assembly. This device comprises, preferably, a'threaded stud 40 which is flattened in its central portion to fit within the U-shaped lugs 30 and 36. A threaded handle 41 is provided for one end of the stud while a second threaded handle 42 is provided for the other end of the dles on the stud the two upper into tight engagement. A pair of bearing pieces 43 are also provided.

In operation, the platform 12 is placed in the base flask member and the locking member 17 placed over the platform. Investment material in plastic form is then placed over and around the platform to fill the cavity be: tween the spaced portions of the platform and the lock ing member 17. The plastic material is added until it is in line with the top ofthe side member so that the edges 22 of member 17 project well above the material.

stud. By turning the han- An aperture 37 is provided in flask flask member hinged to the other end thereof, a removable platform member fitted into said bottom flask member, and a locking membersuperposed on said platform, said locking member having spaced, upstanding prongs that project, when the aforesaid three flask members are in molding relationship, into the cavities of the upper flask members which are provided to receive investment material so that when the aforesaid'flask members are filled with investment material and brought into molding relationship said prongs of the locking member project from the investment material in the bottom flask member and are embedded in the investment material in the upper flask members.

flask members are brought a A metal bridge or denture having a full plate e.g. 50 is then embedded in the investment material with the wax teeth formed thereon aligned with the surface of the investment material which is permitted to harden. There-. after, investment material in plastic form is placed in one upper flask member which is then swung into engagement with the wax teeth pattern so that an impression of the outer surface of the teeth is formed in the investment material. The edges 22 of member 17 extend into the material so that after the material hardens .there can be no lateral shifting between the upper and the lower flask members. Next, the other upper flask memberis filled with soft investment material and it is swung into engagement with the remainder of the flask, so that the wax teeth pattern forms a mold in the material. The clamping device is then employed to lock the three flask members into a rigid assembly. Since the ridges 22 of locking member 17 extend into the material of the second upper flask member, there can be no lateral shifting of this piece with the investment material hardens, the mold is completed and the flask may be opened and the wax removed from the metal bridge, as by placing the flask in boiling water. The acrylic material used to form the teeth of the dentures is then placed in the mold cavity and the flask is locked up with the clamping device. Since there are grooves formed in the hardened investment material in the upper flask members they coact with the projecting ridges 22 of locking member 17 to provide an absolutely rigid assembly. The result is a set of are a faithful reproduction of the, original wax teeth used as a pattern. The acrylic material is then cured to secure its integration with the metal bridge. Thereafter, investment material in which the completed bridgework is embedded is removed from the flask and the bridgework is dislodged by tapping the hardened investment material with a suitable tool.

Inasmuch as many apparently different embodiments of the invention can be made without departing from its respect to the bottom member. After acrylic teeth that spirit on scope, it is intended that what has been shown specification be iriand not in a limiting sense.

hinged dental flask adapted as of acrylic dentures or a complete 2. A three member hinged dental flask adapted for forming extensive units of acrylic dentures or a complete arch bridge comprising a bottom flask member having upstanding side members on opposite sides thereof, a removable platform member fitted into said bottom flask member and having a central arch portion adjacent said side members, a locking member adapted to be fitted over the arch portion of said platform member and having at least one prong member that is spaced from a side member and which extends above the height of the side members so that when the bottom flask member is filled to the height of said side members with investment material said prong member projects from the surface of said material, an upper flask member provided with a cavity to receive investment material and hinged to one end of said bottom flask member so that when said upper flask member is filled with investment material and pivoted into molding position said prong member will be embedded therein, a second upper flask member provided with a cavity to receive investment material and hinged to the other end of said bottom flask member so that when said upper flask member is filled with investment material and pivoted into molding position said prong member will be embedded therein, and a clamping device for clamping the two upper flask members together when in molding position.

3. A three member hinged dental flask adapted for forming extensive units of acrylic dentures or a complete arch bridge comprising a bottom flask member having upstanding side members on opposite sides thereof, a removable platform member fitted into said bottom flask member and having a central arch portion adjacent said side members, a locking member adapted to be fitted over the arch portion of said platform member and having at least one prong member that is spaced from a. side member and which extends above the height of the side members so that when the bottom flask member is filled to the height of said side members with investment material said prong member projects from the surface of said material, said locking member being further characterized, in that the spacing between the prong member and one side wall is occupied by the locking member provided with a cavity to receive investment material and, an upper flask member hinged to one end of said bottom flask member so that when said upper flask member'is filled with investment material and pivoted into molding position said prong member will be embedded therein, a second upper flask member provided with a cavity to receive investment material and hingedto the other end of said bottom flask member so that when said upper flask member is filled with investment material and pivoted into molding position said prong member will be embedded therein, and a clamping device for clamping the two upper flask members together when in molding position.

References Cited in the file of this patent UNITED STATES PATENTS 1,834,980 Stealy Dec. 8, 1931 2,539,740 Harris Jan. 30, 1951 2,604,661 Karns July 29, 1952 

